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Jan. 31, 2012 -- Close to 1 in 4 breast cancer patients who have partial mastectomies undergo a second surgery to remove suspicious tissue, but there is little agreement about when the second surgery is needed.

Researchers found huge variations from institution to institution and from surgeon to surgeon in the rate of follow-up surgeries women had after breast-conserving surgery.

The study found that some surgeons almost never performed second surgeries while others performed them in 70% of their patients.

Partial Mastectomy Second Surgeries Common

Close to 3 out of 4 women with breast cancer in the U.S. opt for breast-conserving surgery.

Follow-up surgery, known medically as re-excision, is performed when there is a suspicion that the initial surgery left behind cancerous tissue.

This is determined when a post-operative report shows cancer cells at or near the outer margins of the removed breast tissue. When margins are positive, meaning that cancer cells extend to the edge of the tissue, a second surgery to remove more tissue is always needed.

But when the margins are negative, it is less clear which patients will benefit from follow-up surgery.

In the new study, published in the Journal of the American Medical Association, researchers examined re-excision rates at four institutions across the U.S.

Wide Variation From Center to Center

Overall, 454 of the 2,206 breast cancer patients included in the analysis had second surgeries following their initial partial mastectomy. Forty-eight women had two additional surgeries and seven women had three re-excisions.

Second surgeries were performed in 86% of women whose initial tissue margins were positive, but when margins were negative re-excision rates ranged up to 70% among surgeons and from 1.7% to 21% among institutions.

“This study establishes that we have quite a bit of variation in how we deliver care to women who have partial mastectomies,” says researcher Laurence McCahill, MD, who is medical director of surgical oncology at the Lacks Cancer Center and a professor of surgery at Michigan State University.

“This issue has not really been part of the conversation between women and their surgeons, but it needs to be,” he says. “I think people will be surprised to find that almost a quarter of women who have partial mastectomies are going back for more surgery.”

Half of Re-excisions Involved Negative Margins

Breast cancer surgeon Monica Morrow, MD, says it is troubling that almost half of re-excisions were performed in women with negative margins, even though it is not clear that these women benefit from additional surgery.

Morrow is chief of breast service at Memorial Sloan-Kettering Cancer Center in New York.

She says aggressive re-excision of margin-negative breasts makes less sense than it once did because almost all patients now have either chemotherapy or hormonal therapy following surgery.

“Big re-excisions may have made sense 20 years ago, but in my opinion they don’t make sense today,” she says.

Stephanie Bernik, MD, who is chief of surgical oncology at Lenox Hill Hospital in New York, points out that decisions about re-excision involve more than just margin status, but she agrees that more work needs to be done to “delineate what constitutes an adequate margin.”

“This paper highlights a major question in dealing with breast cancer: When is a margin good enough?” she says. “Unfortunately, a clear answer to the question does not exist, as there has been no prospective trial looking at this question, and because all situations are not equal.”